JPH02276405A - Compressed-gas-insulated switchgear - Google Patents

Abstract

PURPOSE:To reduce disconnector surge voltage and to improve reliability of insulating performance by forming a sequence so that an earth switch may be closed in opening a disconnector or two disconnectors while a circuit breaker is in an open state. CONSTITUTION:A sequence is found so that earth switches 9 or 6 may be closed after the opening of a disconnector 7 or disconnectors 2 and 3 so that it or they may be closed and opened before the initial closing of either the disconnector 7 or disconnectors 2 and 3. On that account, after the opening of the disconnector 7 or disconnectors 3 and 3, the DC voltage remaining in a conduit between the disconnector 7 or disconnectors 2 and 3 and a circuit breaker 1 is discharged through the earth switch 9 or 6. Consequently, in opening either the disconnector 7 or disconnectors 2 and 3 no residual DC voltage is in the conduit between the circuit breaker 1 and the disconnector 7 or disconnectors 2 and 3 in the initial closing and the foreign material is dropped on the tank side which is insulatingly safe. Since there is no residual voltage, the disconnector surgevoltage generating in closing the disconnector is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a gas insulated switchgear that takes measures against foreign substances in a conduit.

(Prior Art) Generally, in gas insulated switchgear (hereinafter abbreviated as GIS), the overall volume has become important. Care has been taken throughout design and manufacturing to ensure that there are no foreign substances inside the GIS, but just in case, the design is such that insulation will not deteriorate even if some foreign substance gets mixed in. That is, the tank side electrical equipment is such that even if an operating voltage is applied to a foreign object, the foreign object will not float up and reach the high voltage conductor. GIS when foreign matter reaches high pressure
However, as long as the foreign matter is on the tank side, the design is such that even if foreign matter gets into the GIS, this drop in insulation will not affect normal operation.

However, when a DC voltage is applied, the tank electric field at which foreign objects reach the high-voltage conductor is significantly reduced, and conventional designs allow foreign objects to reach the high-voltage conductor. In order to avoid this, the tank electric field must be lower than the normal 175, and the tank diameter must be increased by at least 5 times.

In such a GIS, a disconnector DS is installed as shown in Figure 3.
When the charging current is cut off in the short pipe line up to the circuit breaker CB, the waveform shown in Figure 4 occurs on the load side, and when the cutoff is completed, in the worst case, the waveform shown in Fig. teeth,
A direct current at the ground wave high value of the operating voltage remains.

(Problem to be Solved by the Invention) For this reason, if foreign matter were to enter the GIS, the foreign matter would reach the high voltage conductor. When the DC voltage has positive polarity, it is difficult for the foreign object to reach the high voltage conductor due to corona ions around it, but when the DC voltage has negative polarity, if the foreign object reaches the high voltage conductor, it will cause the foreign object to reach the high voltage conductor, contrary to the positive polarity. It is generally known that foreign objects remain attached to high voltage conductors due to the presence of corona ions around the foreign objects. If the disconnector is turned on with foreign matter attached to the high-voltage conductor, there is a risk of dielectric breakdown due to the surge of the disconnector when the disconnector is turned on, as shown in FIG.

The purpose of the present invention is to eliminate the danger of foreign objects adhering to high-voltage conductors due to the DC voltage remaining in the load-side conduit after the electrical current is interrupted by a disconnecting switch, and dielectric breakdown caused by the subsequent surge of the disconnecting switch occurring when the disconnecting switch is turned on. The object of the present invention is to provide a gas insulated switchgear which eliminates the problem and improves reliability in terms of insulation performance.

[Structure of the Invention] (Means for Solving the Problems) In the gas-insulated switchgear of the present invention, the circuit breaker, the disconnector, and the grounding switch each have an electric appliance body housed in a sealed container filled with SF6 gas. Each component electrical device is interconnected so that one outlet terminal of the circuit breaker is connected to the main body through the main body side disconnector, and the other outlet terminal is connected to the cable head through the track side disconnector. In a gas insulated switchgear configured in a connected manner, a grounding switch is provided between the circuit breaker and the disconnectors on both sides, and the circuit breaker and the grounding switch are remotely operated by electric power or air, and the circuit breaker is This is characterized in that a sequence is set such that when one or two of the disconnectors open in an open state, the earthing switch closes.

(Function) In the present invention, since the earthing switch closes after the disconnector is opened, the DC voltage remaining in the conduit between the disconnector and the circuit breaker is discharged through the earthing switch. Therefore, there is no residual DC voltage in the conduit between the circuit breaker and the disconnector, and foreign matter is steamed to the tank side, where it is insulated and safe. Furthermore, since there is no residual voltage, the disconnector surge that occurs when the disconnector is turned on is also reduced.

(Example) The present invention will be described below with reference to an example shown in FIGS. 1 and 2. FIG. 2 is a single line diagram of the power transmission line A in the gas insulated switchgear of the present invention, and the configuration of the gas insulated switchgear is shown in FIG. 1.

In FIG. 1, one outlet terminal of a circuit breaker 1 is connected to main buses 4 and 5 via a bus-side current transformer CT1 and bus-side disconnectors 2 and 3, respectively.

An earthing switch 6 is connected between the busbar side disconnectors 2 and 3 and the current transformer CT1.

The other outlet terminal of the circuit breaker 1 is connected to the line side current transformer CT2.
and is connected to the cable head 8 via the line-side disconnector 7. In the present invention, earthing switches 9 and 10 are connected to both sides of the line-side disconnector 7, respectively, and further an arrester 11 (FIG. 2) of the earthing switch 10 and the cable head 8 is connected.

These disconnectors 2, 3.7 and earthing switch 6゜9.1
0 is configured so that it can be operated remotely using electric power or air.

Therefore, in the present invention, the earthing switch 9 is the circuit breaker 1.
The sequence is set such that the circuit is closed once under the same conditions as the disconnector 7 and the disconnector 7 is closed, or the circuit is closed and opened once each before the disconnector 7 is closed.

In addition, the earthing switch 6 is connected to the disconnector 7 and 2 under the same conditions as the circuit breaker 1.
The sequence is set such that the circuit is closed once under the same conditions as , or one of the disconnectors 7 and 2 is open, and the circuit is closed and opened once each before closing the other one. Roughly, the earthing switches 9 and 6 can be opened and closed individually many times under the same conditions as the circuit breaker 1 and the disconnector 7 and the circuit breaker 1 and the busbar disconnector 2.3.

Next, the operation of the gas insulated switchgear of the present invention configured as described above will be explained. In the present invention, after the disconnector 7 or the disconnectors 2 and 3 are opened, the earthing switch 9 or 6 is closed.
Alternatively, the sequence is set so that the circuit is closed and opened before the first closing of either the disconnector 7 or the disconnectors 2 and 3.

Therefore, after the disconnector 7 or the disconnectors 2 and 3 are opened, the DC voltage remaining in the conduit between the disconnector 7 or the disconnectors 2 and 3 and the circuit breaker 1 is discharged through the earthing switch 9 or 6. Therefore, when either disconnector 7 or disconnectors 2 and 3 closes first, circuit breaker 1 and disconnector 7 or disconnector 2
There is no residual DC voltage in the conduit between and 3, so foreign objects are dropped onto the insulatively safe side of the tank. Furthermore, since there is no residual voltage, disconnector surges that occur when the disconnector is turned on are also reduced.

[Effects of the Invention] As described above, in the present invention, a grounding switch is provided between the circuit breaker and the disconnecting switch, and the disconnecting switch and the grounding switch are electrically or pneumatically operated so that they can be operated from a distance. driven,
By creating a sequence in which the earthing switch closes once after the disconnector is opened, or closes and opens once each before the disconnector closes, when the disconnector is closed, the Since there is no residual voltage in the conduit between the disconnector and the disconnector, it is on the tank side which is insulated and safe even if foreign matter gets mixed in, and since there is no residual voltage, the surge that occurs when the disconnector is closed. This also makes it possible to provide a gas-insulated switchgear with high insulation reliability.

[Brief explanation of drawings]

Figures 1 and 2 are a configuration diagram and a single line diagram showing an embodiment of the gas insulated switchgear of the present invention, and Figure 3 is a disconnector.
Figure 4 is a single line diagram showing the circuit breaker system;
The figure shows a typical oscilloscope when a line with residual charge is turned on by a disconnector. 1... Breaker 2.3... Busbar side disconnector 4.5... Main busbar 6... Earthing switch 7... Disconnector 8... Cable head 9.10... Grounding Switch 11...Arrester CT1...Bus bar side current transformer CT2...Line side current transformer agent Patent attorney Noriyuki Ken Yudo Ken Daishimaru Figure 2

Claims (1)

[Claims] The circuit breaker, disconnector, and earthing switch each consist of an electric appliance housed in a sealed container filled with SF_6 gas, and one outlet terminal of the circuit breaker is connected to the main body via the mother body side disconnector. In a gas-insulated switchgear configured by interconnecting each component electrical appliance so that the other outlet terminal is connected to the cable head via a line-side disconnector, there is a wire between the circuit breaker and the disconnectors on both sides. Each circuit breaker is equipped with a grounding switch, and the circuit breaker and the grounding switch are operated remotely by electric power or air, so that when the circuit breaker is open and one or two of the disconnectors open, the grounding switch closes. A gas insulated switchgear characterized by a sequence.